1. Field of the Invention
This invention relates generally to surgical instruments used in minimally invasive procedures performed under either direct, endoscopic, fluoroscopic or other visualization and more specifically to a surgical instrument used to capture and remove foreign objects or excised tissue from body canals, cavities, and organs.
2. Background of the Invention
Existing surgical devices for grasping and removing foreign objects from body organs or cavities include mechanically actuated forceps, mechanically actuated snares or mechanically actuated baskets. Each of these surgical devices may be positioned within the body under direct, endoscopic, fluoroscopic or other visualization.
Mechanically actuated forceps usually have two to four arms or prongs, each arm typically ending with a hooked tip. Each arm is typically composed of flat or round stainless steel and is connected at the end opposite the tip to a handle used to position and grasp. Most mechanically actuated forceps include an inner and outer sheath. The outer sheath is fixed with respect to the handle and the inner sheath may be advanced from or retracted into the outer sheath. When the inner sheath is retracted into the outer sheath, the arms spread from each other, allowing the forceps to be advanced toward and around an object within the body sought to be captured or removed. The arms of the forceps are then tightly closed about the object by extending the inner sheath from the outer sheath in the direction of the tips, whereupon the arms are urged together to encircle and grasp the object sought to be captured or removed.
Mechanically actuated snares preferably include a loop of wire enclosed within a sheath. The loop of wire can be extended beyond the sheath to form an oval opening. The size of the oval opening is controlled by the length of wire advanced beyond the end of the sheath. In use, after the snare is positioned adjacent the object, the wire is advanced beyond the end of the sheath until a loop larger than the object is formed. The loop is then positioned until the plane of the loop encircles the object. The sheath is then advanced and the wire retracted so that the loop closes around and ensnares the object.
Several of the snare-type surgical devices also incorporate a sack associated with the snare to trap the object to be captured or removed. One example includes U.S. Pat. No. 5,190,555 which includes a sack of a flexible material and further requires a drawstring to open and close the sack. Another example is U.S. Pat. No. 5,192,286 which includes a net which can be collapsed to facilitate introduction into the body lumen and opened in situ to permit capture and retrieval of an object therein. The net is opened by a flexible loop member. Another example is U.S. Pat. No. 5,354,303 which includes a flexible sac and a resilient or spring loaded rim member disposed about the opening to urge the opening to an open configuration when deployed in the body cavity.
Mechanically actuated baskets typically include three to six wires enclosed within a sheath. The wires are joined at a first end with a handle and are joined at a second, distal, end to each other. Advancing the wires beyond the sheath forms a basket. The volume of the basket is controlled by the length the wires are advanced beyond the sheath. In use, the closed basket is positioned adjacent the object to be captured or removed and a portion of the wire is advanced beyond the sheath to form a basket of sufficient volume to enclose the object. The basket is then positioned until the object is within the basket. The wires are then retracted into the sheath shrinking the volume and pulling the object against the end of the sheath. The smaller the object, the more wires are needed to trap and hold the object. Conversely, large stones will not be able to work their way between closely spaced wires for capture.
Surgical instruments of the prior art have important limitations. First, they are mechanically complex, particularly mechanical baskets, and are therefore difficult, time-consuming and expensive to manufacture. Second, positioning such prior art surgical instruments to effectively grasp the object to be removed is difficult. This is particularly true where the surgical procedure requires a surgical device which can capture or remove objects with a capturing portion which is generally perpendicular to the longitudinal axis of the surgical device. One example of such a procedure is where the object to be captured or removed is present in a blood vessel or is a kidney stone present in the ureter. Third, positioning such prior art surgical instruments extends the duration of the surgery and increases the risk to the patient. Fourth, where wires of sufficient elastic strength to open and close about an object are used, the rigidity of such wires contributes to trauma of sensitive tissue surrounding the object to be captured or removed during positioning. Fifth, where the surgical instrument includes a sack for capturing objects to be removed, the sack cannot be emptied in the body canal, cavity or organ. Hence, once captured, the object and sheath must be removed from the body canal, cavity or organ regardless of the trauma thereto. This is particularly true when the size of the object is greater than the size of the body canal, cavity or organ, or the openings therein, through which the object is to be removed.
It is an object of the present invention to provide a surgical device capable of capturing and removing an object from body canals, cavities and organs which is not mechanically complex, is easily positionable and will minimize trauma to sensitive tissue surrounding the object to be captured or removed. It is an object of the present invention to provide a surgical device which is relatively easy to manufacture and which has a capturing portion positionable generally perpendicular to a longitudinal axis of the surgical device. It is an object of the present invention to provide a surgical device which includes for capturing an object a sack which can be emptied inside a body canal, cavity or organ.